Clinical assessment of injuries in orthodontic movement of impacted teeth. I. Methods of attachment.

Recent studies have indicated ankylosis, loss of attachment, and external resorption occurring as sequelae of orthodontic movement of impacted teeth when these teeth are ligated around the cervix with wire. The purpose of this study was to record the effects of two commonly employed methods of attachment to impacted teeth--the wire ligation and the direct bond. Twenty subjects who had previously undergone full-banded orthodontic treatment involving a unilateral impacted maxillary canine were studied. The contralateral non-impacted maxillary canine served as a control. In eight of the subjects the impacted canine was ligated at the cervix with wire at the time of surgical exposure. In the other twelve subjects the impacted tooth also was exposed surgically but then an orthodontic bracket was bonded directly to the tooth approximately 2 weeks after the surgical exposure. The criterion for the diagnosis of ankylosis was failure to move the tooth for at least 3 months. The diagnosis of external resorption was made from radiographs. Loss of periodontal attachment was measured by comparing the level of attachment on the previously impacted tooth with the contralateral canine 3 months after debanding. The results indicated that three of the eight patients in the group receiving wire ligation exhibited external resorption and ankylosis. Also, there was an average of 1.36 mm. greater loss of attachment in all four proximal and lingual probing measurements of teeth ligated with ligature wire but no significant differences in the direct buccal probing measurement.